you can do just the short block, and keep the wrx heads. they are very limiting for a lot of power, so people usually just do the long block since the engine is coming out anyway and it will save time/money, plus will give you more of what you want. the shortblock is a good deal, and if you're looing for 300-330whp on pump fuel with nice spool up, a sti shortblock is the way to go. on the flip side, going with a vf30/34 or something is a waste. either of those turbos aren't going to match well. with a turbo as small as the vf30/34. with either one of those, you're going to get spool incredibly early and have zero top end. it will be somewhat like the stock turbo. while that's not necesarily a bad thing, not worth the time money to go through putting in a shortblock for measly power goals. this is an an opinionative thing, some will disagree, and some will also agree.Originally posted by fatgroundhog
Anybody have the short version of a complete 2.5 engine swap? A short block only runs about $1k used, and I thought the heads from the WRX would fit. What else is involved, other than the ECU and turbo?
the stock wrx ic actually can handle about 300whp without many problems, it flows very well in fact. to get those kind of results, you're going to need extensive dyno tuning and plan on many many hours for it. the wrx stock ic has a pressure drop problem at those levels, i.e. it heats up incredibly fast with that power, obviously, which is why people just go with a fmic to alievate that.
the stock wrx cr is 8.0, while that's ok, that's not the sweet spot for a turbo car. depending on want, need or whatever else, you'd want either an 8.5 cr, whcih most people shoot for, or some with a 9.0 cr. there are just practical limits to pump gas, and once you reach them, the only way to make more power is to have a higher cr, therfore needing less timing and less boost to achieve the same or higher results. race gas would be the other exception, as you can advance the timing a good 3 degrees across the board. getting a larger turbo, that flows more, is another way, but in the end you are either sacrificing spool (to get large power on pump, 5000+ spool), and who wants that with a redline of 7000. it's really an illusion, there is just so much you can do with pump fuel. sure, a green can make around 375whp on pump, but have you seen a dyno of it? it's horrid. this is why I went with an 1818, and nothin bigger. got the spool I wanted, with some top end. the 1818/1820 also respond better to pump fuel then the 18g does, although the 18g/20g series respond better with race fuel.
did I miss something?